1. Field of the Invention
The present invention relates to bearing structures for a motor rotor, wherein a bearing structure with an axle hole is pressed and tightly fitted into an axle tube without causing deformation in an inner periphery defining the axle hole. A shaft of the rotor pivotally supported in the axle holes of the bearing may rotate smoothly without deviation.
2. Description of the Related Art
FIGS. 1 and 2 of the drawings illustrate a conventional motor rotor having a shaft 91, a bearing 92, and an axle tube 93. The bearing 92 is generally an oil-pregnant copper bearing or non-ball type bearing. The bearing 92 is pressed into an interior of the axle tube 93 so as to be tightly engaged to an inner periphery of the axle tube 93. The inner periphery radial deformation occurs during forced fitting of the bearing 92. Adverse affection to rotation of the shaft 91 of the rotor occurs even though the deformation is very minor. As a result, rotational noise is generated and the motor operating life is shortened. More specifically, the length of the inner periphery of the bearing 92 is approximately the same as that of the outer periphery of the bearing 92 such that when the bearing is forced fitting into the axle tube 93, the inner periphery 94 defining the axle hole of the bearing 93 resulted in irregular deformation. As a result, smooth surface of the shaft 91 becomes in contact with deformed inner periphery 94 of the axle hole of the bearing 92. Accordingly, noise is generated during rotation of the shaft 91 and the motor operating life is shortened.